Concepts to improve your cognitive toolkit?

I know, I know -- I still think you and JT, if forced to work together for awhile, could make for a classic "buddy movie" scenario wherein at the mid-point there's a fantastic knock-down drag-out fight, and afterwards you both end up a little more humble. :-)

The movie, "Step Brothers" comes to mind... :-)

Oh well... good luck with it.

I did a project in college with a couple of other guys where we used Fourier analysis of software branches to design a better branch predictor than the traditional ones. It actually worked pretty well, and we wrote it up and give our presentation to the class, making sure to site the statistics the right way: Something like boldly proclaiming, "Our techniques is twice as good as the traditional technique, mispredicting branches only half as often!," but then leaving it to some fine print on an obscure slide to mention that um... the traditional technique was already correct something like 98% of the time, so OK, we were correct 99% of the time -- hence our technique had a negligible impact on overall execution time.

(And unlike some projects, I feel no shame whatsoever on that one -- the professor approved the topic in the first place, and he certainly was well aware that there wasn't significant room for improvement to be had. He was probably also just curious if it'd work at all...)

At least your TDR there is actually *useful!*

---Joel

And I let you know your pretentions. I may remind you next time you ask another to stop posting. Or not. Anyway, 'nuff said. Climate posts here are okay by me. Yours included. Your pretentions are a bit sad, is all.

Jon

Joh Kirwan doesn't post all that often. He and I do post detailed responses to your brief inanities, but "1%" is clearly one of those ivneted statistics of which you are so fond.

You own ranting about climate ae equally off topic, and - since they are pretty much always ill-informed and incorrect - rather worse than usueless. Pointing out your incorrigible enthusiasm for posting the same non sequiteurs time after time is rubbing your nose =3Din your mistakes, but since you don't learn anything from the experience, I suppose we have to concede that it is useless to you, though t may be educational for the less brain-damaged lurkers.

They are being tested all the time, albeit at a rather more subtle level than gets reported in the right-wing media. Since we need to start cutting CO2 emissions now, and the models are providing the evidence for that proposition, they are testable within a useful time frame.

It's a pity that the arguments and effects are too subtle to get publicity in the right wing media - which is in any event rife with denialist propaganda - but much as everybody would prefer to be able to sit on their hands until climate change had produced an undenialbe catatastrophe or two, the way climate change works means that waiting that long would be a very bad idea.

Not true - you may not know enough to recognise the fact, but Jon Kirwan and I both know rather more about the subject than you do, and distinctly more than "essentially nothing" and we have the further advantage that what we do know is based on the scientific evidence, rather than ill-digested denialist propaganda.

Perhaps, but it could be falsified, and fifteen years of attempted falsifications haven't produced a convincing alternative hypothesis.

ults.

You experience having you daft deas shown up as daft as "being insulted". Tough.

Scarcely a couple.

The fact that Bond event show up every 1500 years does suggest that there are some regularities in the system. Whether we can assemble and digest enough data to concoct a simulation that is good enough to simulate these regularities is obviously an open question.

All we can say at the moment is that it doesn't seem to be impossible. Anybody who did prove that was impossible would be able to publish the proof in Science or Nature, and would do very well out if it.

-- Bill Sloman, Nijmegen

I may have a better idea about it after I've finished reading "Atmospheric and Oceanic Fluid Dynamics." It's not a light book, so it may be some time yet. But at least it helps that I've at least some glancing familiarity with vector calculus, so I have a modest, fighting chance.

In the meantime, you might actually crack a book on the subject before pontificating from ignorance.

Jon

I just learned a few things, already. Nice paper. Thanks.

John L. will not be able to summarize in his own words the content of even the first page.

Jon

P.S. Dynamical systems on the KAM torus surface can transition to other points on the surface (I think it highly unlikely of course) and so long as the path stays on the surface the Lyapunov exponent will stay zero. But what's also interesting, and I think almost as obvious, is that it must then follow that for systems moving from the KAM surface transversely off of it, but while still _near_ the KAM surface, must also exhibit a Lyapunov exponent of zero. An interesting implication to me being that dynamical systems can stay near the KAM torus for a __very__ long time. I'm having a hard time expressing why I think so, but intuitively it feels right. Anyway, thanks for the pointer. More to think about and study and I like that.

Larkin must be a leftist pansy, following the methodology of calling others the names that the leftist pansies actually are.

Larkin, Don't be a continual dupnik. ...Jim Thompson

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Every once in a while the failures are so bad, that you leave it 'dead at the side of the road'. Because it was 'so stupid'... and yet so educational.

Big mistakes seem to happen less often as you get older, (and big sucesses too?) Sometimes doing something 'stupid' works for reasons that aren't understood until after.

George H.

Think about the situation: we have immensely complex ocean basins, boundaries, and subsurface geometry. Water is moved, at the crudest level, by thermal gradients, which come from the sun (interacting in both directions with cloud cover, chaotic weather, storms; orbital dynamics); interaction with the atmosphere; and a complex heat flux coming up from chaotic magma flows. Density varies with salinity (modified by rivers, whose flow depends on weather, and ice melts (like unpredictable ice shelf breakaways) and temperature (water having an unusual density-temperature curve) and silt loading and pressure. There is lots of stratification, breeding ground for R-T instability. Then we have lunar and solar tides to add to the fun. Everything will interact nonlinearly. The smallest stream displays chaotic turbulent behavior; big rivers are erratic at the millions of cubic feet per second level. It boggles the mind that ocean currents would somehow order themselves enough to usefully model. A million bouys, a billion bouys, wouldn't extend the modeling horizon another year.

A lava lamp is simple by comparison.

John

Well, there's an abstract there already.

Given the initial conditions, and classical math, the pure many-body orbital system can, in theory, be predicted forever. Most such systems have no known closed-form solution, so the next best bet is simulation. But the tiniest variation, errors in measurement, floating point errors, quantum uncertainty, make the numerical solutions diverge wildly. So things may be flung out, things may crash into a heap, things may orbit sedately forever, all because of some tiny change. Some systems are extremely sensitive to that, some not at all.

Which is why I'm skeptical of climate simulation. The systems are as messy as imaginable, if not more so, the rules aren't known, the feedbacks are powerful and nonlinear, initial conditions can never be known, and random external forcings abound. The gross average sorts of things that might be predictable allow a range of time behavior that will profoundly affect life.

Orbital dynamics is like clockwork compared to climate.

What's your experience in simulating strongly nonlinear systems? I'm about to embark on closed-loop controlling a really nasty one, with gigabuck consequences. Wish I could talk about it.

John

It's unfortunate that we sometimes do things we don't understand, just because they happen to work.

John

I _am_ thinking about the situation. First, I need to develop the mental tools -- something you might do rather than pontificating as though you've trained yourself on the specific details. At least I'm spending time studying the _right_ textbooks. And I also know scientists have been successful, to a degree, at approaching aspects of this problem, too.

Argument from extremes. Ignored.

Jon

I've been simulating, and building, nonlinear systems most of my life. How about you?

But a lava lamp *is* simple. It's the planetary system that's extreme.

John

I actually do NOT believe your personal approach is ever systematic. Not that I doubt you hire smart people to do it for you. But if you did this yourself, I wouldn't see your poor and repeated ignorance, over and over again here.

For me, only a few times. Load changes in process control. But I retain enough of theory to at least know enough to say that you've no clue.

Martin's discussion was interesting because I've studied Gilmore's book on catastrophe theory (written right around the same time that Sain and Massey ("Invertibility of linear time?invariant dynamical systems"), and Silverman ("Controllability and observability of time?variable linear systems" and "Inversion of multivariable linear systems"), were publishing on invertibility problems, and have glancing experience with perturbations as applied to orbital mechanics. The discussion he offered was very interesting as it relates to chaos theory and attractors and it rekindled my desire to study that area more.

I've done orbital mechanics and some perturbation theory. So far, your point still doesn't present an argument to me.

Jon

I've been, personally, simulating complex nonlinear systems, electronic and physical and mathematical, since I was an undergraduate. My first serious one was a 32,000 horsepower steamship, simulated on an HP9100 programmable calculator, quickly moved to a PDP-8. Sure, some of my guys do sims too; everybody does these days. Rob just designed a neat matched filter, for detecting particles crossing a laser beam, using an adaptive learning algorithm. Those algorithms can be wild and chaotic, too, if you're not careful.

Well. Then I probably know more about this stuff than you do.

The solar system orbits are not very chaotic, in that hundreds of years ago people were predicting planetary positions and eclipses accurately, without benefit of computers, with their numbers good over thousands of orbits. More chaotic systems may have no obvious periodicities and aren't predictable to any usable extent.

John

John "Dupnik" Larkin probably doesn't know even Lyapunov's second method. I had that under my belt many years before there were simulators ;-)

Oh, I know... his wife went to BU (that's supposedly a slur in Larkin's twisted mind :-) ...Jim Thompson

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One can understand why you might put foreard that opinion. Your judgement isn't going to be disinterested and it certainly isn't well- informed.

-- Bill Sloman, Nijmegen